Luminaire closure device

ABSTRACT

Luminaire with housing of pyramidal shape open at its bottom has a light transmitting bottom door with a frame formed at one side with a hinge portion detachably fitting into the bottom frame of the housing. The hinge is detachable only when the door is swung open to a predetermined angle. Channels formed in the housing frame and in the door frame receive screws for holding the four sides of each frame in assembly. Recesses in the door frame side opposite the hinge side receive a threaded portion of the captive locking screws in that side to enable the door to be opened when the captive screws are retracted. Other recesses in the door frame sides receive a ridge on the adjacent housing frame sides in the closed position of the door to prevent light leakage through the closure joint.

United States Patent 1 Murray et al.

[451 July 24, 1973 LUMINAIRE CLOSURE DEVICE Inventors: Omer E. Murray; Robert G.

Kilpatrick, both of Hendersonville, N.C.

Assignee: General Electric Company Filed: Apr. 24, 1972 Appl. No.: 246,914

[1.8. CI 240/147, 240/11, 240/84 Int. Cl. F21v 21/00 Field of Search 240/11, 11.2, 41.55,

References Cited UNITED STATES PATENTS 8/1965 Moore 240/78 R 5/l965 Muller et a1. 240/147 X Primary Examiner-Joseph F. Peters, Jr. Attorney-Sidney Greenberg et al.

[5 7 ABSTRACT Luminaire with housing of pyramidal shape open at its bottom has a light transmitting bottom door with a frame formed at one side with a hinge portion detachably fitting into the bottom frame of the housing. The hinge is detachable only when the door is swung open to a predetermined angle. Channels formed in the housing frame and in the door frame receive screws for holding the four sides of each frame in assembly. Recesses in the door frame side opposite the hinge side receive a threaded portion of the captive locking screws in that side to enable the door to be opened when the captive screws are retracted. Other recesses in the door frame sides receive a ridge on the adjacent housing frame sides in the closed position of the door to prevent light leakage through the closure joint.

10 Claims, 6 Drawing Figures PATENTED JUL 2 4 I973 sum 2 2 .nu!!!uuum LUMINAIRE CLOSURE DEVICE The present invention relates to closure devices and more particularly to a closure device for luminaires.

It is an object of the invention to provide an improved frame and hinge structure for closure devices, and particularly for light transmitting doors for luminaires and the like.

It is a particular object of the invention to provide a luminaire closure of the above type having a rectilinear frame comprising a plurality of similarly formed sides, one of which has a hinge portion formed thereon.

Still another object of the invention is to provide a luminaire housing frame which is complementary to and cooperates with a closure of the above described type, and to which the closure frame hinge is captively secured except at a predetermined open position in which it is readily detached.

A further object of the invention is to provide a closure of the above type for the bottom of a post top luminaire wherein the closure may be readily opened even in the installed position of the luminaire to provide access to the interior of the luminaire for servicing operations.

Still another object of the invention is to provide a closure of the above type which is readily and economically manufactured.

Other objects and advantages will become apparent from the following description and the appended claims.

With the above objects in view, the present invention in one of its aspects relates to a luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to the housing surrounding the bottom opening, one of the frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering the bottom opening of the housing comprising a panel and a frame comprising a plurality of side members corresponding to the plurality of housing frame side pieces surrounding the panel in engagement therewith, one of the closure frame side members being formed along its length with an elongated hinge portion received in the C-shaped recess of the housing frame for rotation therein for movement of the closure relative to the housing frame between open and closed positions, the hinge portion being formed with stop means co-acting with the recess wall portion to prevent removal of the hinge portion from the C- shaped recess until the closure is rotated to a position away from the housing bottom opening wherein the stop means clears the wall portion, and means for detachably holding the closure in its closed position.

The invention will be better understood from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a post top luminaire embodying the present invention;

FIG. 2 is a view of the FIG. 1 luminaire showing its bottom closure in partially open position;

FIG. 3 is an enlarged cross-sectional view of the cooperating hinge portions of the luminaire housing frame and closure frame with the door in closed position;

FIG. 4 is a similar view showing the closure frame being detached from the housing frame;

FIG. 5 is a cross-sectional view of a portion of the luminaire and closure frames showing the closure locking means; and

FIG. 6 is a perspective view of a corner portion of the closure frame.

Referring now to the drawings, and particularly to FIG. 1, there is shown a decorative post top luminaire 1 comprising a housing 2 of pyramidal shape formed, for example, of suitable sheet metal. Housing 2 is closed at its top and has a square bottom defined by a frame 6. The bottom opening is closed by a door 3 comprising a light transmittting panel 4 such as plastic, glass or other suitable material held at its periphery by a frame 5. Luminaire l is mounted on the top of post 10 at its central base 7 to which housing 2 is secured by suitable brackets 8 (see FIG. 2) and on which lamp 9 is suitably mounted extending upwardly within housing 2. Housing frame 6 surrounding the bottom opening comprises an assembly of four side pieces 6a, b, c, d of identical form. Door frame 5 comprises an assembly of four side members 5a, b, c, d which are of the same form except for the hinge side member 5a as more fully disclosed below. Both frames 5 and 6 are typically made of metal, such as aluminum, although other suitable materials may be employed. Frames 5 and 6 are so proportioned and arranged that closure frame 5 nests within the bottom of housing frame 6.

Each of the frame side members are formed with an inwardly opening slot 11 in which the periphery of light transmitting lens or panel 4 is received. Panel 4 fits into slot 11 with some clearance to allow for expansion due to heating under operating conditions. Projecting from the outer side of frame member 5a only and extending parallel thereto is an elongated cylindrical hinge portion 12 joined to the main portion by an angle portion 13. In its intermediate portion, each side member of frame 5 is formed with an elongated circular recess 14 for receiving at the end thereof a screw 15 (see FIG. 6) which fastens the frame member to the adjoining frame member. Circular recess 14 opens at its top to an upper recess 16, the purpose of which will be explained below in connection with locking frame member 5c. Each closure frame member is formed on its upper surface adjacent its inner side with a channel 17 which in the assembly shown in FIG. 3 receives a ridge 20 formed along the bottom surface of the adjacent housing frame member. Ridge 20 in combination with channel 17 serves as a light trap to prevent leakage of light from the luminaire through the closure joint and thereby avoid the attraction of insects which might otherwise tend to enter the luminaire housing.

Housing frame member 6a, which is identical in form to the remaining three housing frame members, has a sloping outer side corresponding to the slope of pyramidal housing 2 and serves in conjunction with the other housing frame members as a decorative trim band and as a reinforcing stiffener for the sheet metal housing, in addition to other functions as described below. Frame member 6a is formed with an inwardly projecting shelf 21 on which bottom flange 2a of the housing rests and is secured thereto by clip 22. Spaced below shelf 21 and projecting inwardly beyond it is ledge 23, which is formed with an elongated circular recess 24 for receiving at the end thereof a screw 25 used for fastening the adjoining housing frame member thereto. Frame member 6a is further formed with a depending hinge support 26 having an elongated concave seat 27 in which hinge portion 12 of door frame 5 is rotatably received, the dimensions of the parts as shown in FIG. 3 being such that in the closed position of door 3, hinge portion 12 and adjoining angle portion 13 fit snugly in the space between concave hinge seat 27 and the bottom of ledge 23. By virtue of this arrangement, hinge portion 12 of frame 5 cannot be detached from its hinge seat 27 until the door 3 is swung open at a sufficient angle so that, as seen in FIG. 4, the corner of angle or stop portion 13 clears the bottom of ledge 23 and permits removal of hinge portion 12 through the space between ledge 23 snd the front edge of hinge seat 27. Door 3 may thus be detached from the luminaire housing without disassembling the frame parts. As also is seen, door frame 5 nests entirely within the bottom opening of housing frame 6 defined by the latters dependent portion 26 with the bottom surfaces of the two frames substantially flush so as to provide a neat, decorative appearance at the closure periphery.

FIG. 5 shows a cross-section of the co-acting door and housing frame members 50 and 6c on the side opposite the hinge frame members 5a and 6a. Door frame member 50 is provided with one or more tapped holes 30 for receiving a captive screw 31 having a threaded portion 31a projecting radially therefrom which threadably engages an aligned hole 32 in ledge 23 of housing frame member 6c for holding door 3 locked in closed position on the luminaire housing. The length of threaded screw portion 31a is such that when screw 31 is unscrewed, its threaded portion 31a drops into recess 16 entirely disengaged from the threaded hole 32, so that the operator need merely unscrew the remaining locking screw or screws to enable door 3 to be dropped into open position while the locking screw 31 remains captive in door frame 5.

Aside from the provision of holes therein for captive screw 31, frame member 5c is identical in form to the other frame members except for hinge frame member 5a in the respects described previously. At its outer side, frame member 5c is formed with a channel or groove 18 having sloped side walls for receiving near an end thereof the flat head of fastening screw 15, as seen in FIG. 6 where such a screw is shown arranged in a corresponding channel 18 in frame side member 5d for connecting it to adjoining hinge frame member 5a. Screw is thus disposed flush with the outer surface of the respective frame members and accordingly does not interfere with the opening and closing movements of door frame 5.

While the present invention has been described with reference to particular embodiments thereof, it will be understood that numerous modifications may be made by those skilled in the art without actually departing from the scope of the invention. Therefore, the appended claims are intended to cover all such equivalent variations as come within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said housing frame between open and closed positions and being laterally removable therefrom, said hinge portion being formed with stop means co-acting with said recess wall portion to prevent removal of said hinge portion from said C-shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position.

2. A luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said housing frame between open and closed positions, said hinge portion being formed with stop means co-acting with said recess wall portion to prevent removal of said hinge portion from said C- shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position, each of said housing frame side pieces being substantially identical in cross-section and each having an elongated recess therein extending the length thereof, and screw means received in an end of said recess of at least certain of said side pieces holding said housing frame side pieces in assembly.

3. A luminaire as defined in claim 2, each said closure frame side members having an elongated recess therein extending the length thereof, and screw means received in an end of said recess of at least certain of said side members holding said closure frame members in assembly.

4. A luminaire as defined in claim 2, each said housing frame side piece having an outer wall portion and a ledge portion extending inwardly from said outer wall portion, said closure frame being nested within said housing frame and in mating relation with the underside of said ledge portion in closed position.

5. A luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion definingan elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said clo sure relative to said housing frame between open and closed positions, said hinge portion being formed with stops means co-acting with said recess wall portion to prevent removal of said hinge portion from said C- shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position, said closure holding means comprising a locking screw in another of said closure frame side members, said looking screw having a threaded portion of predetermined length at one end projecting radially therefrom and thrcadably engaging said housing frame, said another closure frame side member adjacent said threaded portion of said locking screw being formed with an opening for loosely receiving said threaded screw portion while captively holding said locking screw.

6. A luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said housing frame between open and closed positions, said hinge portion being formed with stop means co-acting with said recess wall portion to prevent removal of said hinge portion from said C- shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position, the remaining housing frame side pieces each having a wall portion corresponding to said first mentioned wall portion, said wall portions extending below said bottom housing opening and defining a closure receiving recess, said closure frame nesting within the latter recess surrounded by said wall portions.

7. A luminaire as defined in claim 6, the outer side of said closure frame members being grooved along their length, and screw means extending through the grooved sides of at least certain of said closure frame side members for holding said members in assembly, said screw means having a-head lying nested within said grooved outer side of said members.

8. A luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprisng a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said'frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side mem- 6 bers corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said housing frame between open and closed positions, said hinge portion being formed with stop means co-acting with said recess wall portion to prevent removal of said hinge portion from said C- shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position, said housing having an inwardly extending bottom flange, said housing frame side pieces each having an inwardly directed shelf portion supporting said housing bottom flange, and fastening means holding said flange in assembly with said shelf portions.

9. A closure arrangement comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said housing frame between open and closed positions and being laterally removable therefrom, said hinge portion being formed with stop means co-acting with said recess wall portion to prevent removal of said hinge portion from said C- shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position.

10. A luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said housing frame between open and closed positions, said hinge portion being formed with stop means co-acting with said recess wall portion to prevent removal of said hinge portion from said C-shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position, said housing frame side pieces being in mating relation with respective ones of said closure frame side other being formed with an elongated ridge received in members in closed position of said closure frame, one said channel for forming a light trap at the junction of of said side piece and said side member in each mating said housing frame and closure frame. pair being formed with an elongated channel and the 

1. A luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said hOusing frame between open and closed positions and being laterally removable therefrom, said hinge portion being formed with stop means co-acting with said recess wall portion to prevent removal of said hinge portion from said C-shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position.
 2. A luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said housing frame between open and closed positions, said hinge portion being formed with stop means co-acting with said recess wall portion to prevent removal of said hinge portion from said C-shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position, each of said housing frame side pieces being substantially identical in cross-section and each having an elongated recess therein extending the length thereof, and screw means received in an end of said recess of at least certain of said side pieces holding said housing frame side pieces in assembly.
 3. A luminaire as defined in claim 2, each said closure frame side members having an elongated recess therein extending the length thereof, and screw means received in an end of said recess of at least certain of said side members holding said closure frame members in assembly.
 4. A luminaire as defined in claim 2, each said housing frame side piece having an outer wall portion and a ledge portion extending inwardly from said outer wall portion, said closure frame being nested within said housing frame and in mating relation with the underside of said ledge portion in closed position.
 5. A luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said housing frame between open and closed positions, said hinge portion being formed with stops means co-acting with said recess wall portion to prevent removal of said hinge portion from said C-shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position, said closure holding means comprising a locking screw in another of said closure frame side members, said locking screw having a threaded portion of predetermined length at one end projecting radially therefrom and threadably engaging said housinG frame, said another closure frame side member adjacent said threaded portion of said locking screw being formed with an opening for loosely receiving said threaded screw portion while captively holding said locking screw.
 6. A luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said housing frame between open and closed positions, said hinge portion being formed with stop means co-acting with said recess wall portion to prevent removal of said hinge portion from said C-shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position, the remaining housing frame side pieces each having a wall portion corresponding to said first mentioned wall portion, said wall portions extending below said bottom housing opening and defining a closure receiving recess, said closure frame nesting within the latter recess surrounded by said wall portions.
 7. A luminaire as defined in claim 6, the outer side of said closure frame members being grooved along their length, and screw means extending through the grooved sides of at least certain of said closure frame side members for holding said members in assembly, said screw means having a head lying nested within said grooved outer side of said members.
 8. A luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprisng a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said housing frame between open and closed positions, said hinge portion being formed with stop means co-acting with said recess wall portion to prevent removal of said hinge portion from said C-shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position, said housing having an inwardly extending bottom flange, said housing frame side pieces each having an inwardly directed shelf portion supporting said housing bottom flange, and fastening means holding said flange in assembly with said shelf portions.
 9. A closure arrangement comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said housing frame between open and closed positions and being laterally removable therefrom, said hinge portion being formed with stop means co-acting with said recess wall portion to prevent removal of said hinge portion from said C-shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position.
 10. A luminaire comprising, in combination, a housing having a plurality of sides defining a bottom opening, a housing frame comprising a corresponding plurality of side pieces secured to said housing surrounding said bottom opening, one of said frame side pieces having along its length a wall portion defining an elongated generally C-shaped recess therein, a closure for covering said bottom opening of said housing comprising a panel and a frame comprising a plurality of side members corresponding to said plurality of housing frame side pieces surrounding said panel in engagement therewith, one of said closure frame side members being formed along its length with an elongated hinge portion received in said C-shaped recess of said housing frame for rotation therein for movement of said closure relative to said housing frame between open and closed positions, said hinge portion being formed with stop means co-acting with said recess wall portion to prevent removal of said hinge portion from said C-shaped recess until said closure is rotated to a position away from said housing bottom opening wherein said stop means clears said wall portion, and means for detachably holding said closure in its closed position, said housing frame side pieces being in mating relation with respective ones of said closure frame side members in closed position of said closure frame, one of said side piece and said side member in each mating pair being formed with an elongated channel and the other being formed with an elongated ridge received in said channel for forming a light trap at the junction of said housing frame and closure frame. 